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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9b6ea35f745bf49c14f02b0ffb0d088d1bb36d98da6df9e6b952591823cb91a' 
  AND token = 'kLHhvUbCAJzG4C4mH9QurTeHvkUs4f0m+GIcJlAGEDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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