SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15840d746b61b757bbd7d187de6d46f34f43a14c0befca9d921382185a2c234a' 
  AND token = 'HFLLJ27jhQ0FE4+wBqsz9dylHxUsMqCNS3gvSIPy+L0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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