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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9f7a8d75586ccf979d17cb21b1d82d25bde55bfcab47ea4ca6fffff491aaf57' 
  AND token = 'L2dAwWuzgQjE7RvQF5sNJRDwIaeizfJk/Yl2MeTTZaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}