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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '794408b8004e50b0cb1bf563b2141a24ddaf33021bfee2d3b57f62ec1d703bd2' 
  AND token = 'Z+J+11ZKJ+q3CudnBy5qP7PkLXzzPcpw7jJ4qWyBiqI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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