SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '547b2cfa73a1b9a16523871293e0801f375c74e2c74cc85238396104f2ba6863' 
  AND token = 'Y5CqYNsC8Inu3b1xKn9y/ysddjF0Bv+LjWYBQgRwAT8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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