SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69303d4728cde378616495295eaa85219ca9736df0ec47e126776597a1fc7e37' 
  AND token = 'tjQKrybb0P6HqfiwPw7cElMJoNRnltNhlNLCFbSlnXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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