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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3f1cb7a7689a47cda307f8a66fdd6bb21ef6cdfadb6134b63d63bc5aec6dbbf' 
  AND token = 'ElrHTJA9GuL6qxWSf5Gmv5daFd1Bf8AF8Koa+ktLhYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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