SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '736c4670848c3ca9c5a18d47bfbd171d03f2b38e907f969250540af635790475' 
  AND token = 'vNS+9BiIYhSbUVK6y9Z9zf/SP82nE1QL3lhVZyUhSS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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