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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3fd21ddd37a5320ed016bf83793191adc69e648d1f244206a4591dec1d8e5d0' 
  AND token = 'BUj9DbygIwMrOKvX5HEEBeTsg8kwvgzyNSlWhm1jDKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}