SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27893ffb23e5657c651217334bbc4a252f914cab62c6965ede32e3df77016331' 
  AND token = 'NzOzBYYd/KehVZ41N0mns1fPN6XHOrDyIVQWltAIYNc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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