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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e6ef9ec55c4c94d20a2cf99bb33b7e923e6928548698efb821d988e1dbb7f61' 
  AND token = 'xVvqDga5SDq22KkljBoX8eoQ9ZIaBb5LSf02ccMiCGk=' 
  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"
    }
  }
}