SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f74b1b4f23af1203a655c1002489c0887804f933ed6201290d6e3cdf896ae8c' 
  AND token = '7vEUSYsZKHwEDm9nhWfHPT96NBiXyhLBYHdKOVffsjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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