SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c326648ee9b984cd0dfca7261ff67af53dc3aaabf9f6303c97727077e703e1b8' 
  AND token = 'ubL1RXTa1oU/YqL6cHzfn5qbOyweDLH2yvCYcYw+UM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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