SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fee7c635a1be539123ee50811f16ffccf878c4726cc6008c51bfd5ab9c8a5a1c' 
  AND token = 'RVo+/5JUhgXH/eecETjxhA1YSvPrnXL1ddOEiRWd7mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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