SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18c814fa5ceb90867b39038c33298fb3e0ba84a34d5dccde9c2b93c09f866066' 
  AND token = 'pcUubEqfShZb2CgtLr9KjBjK6YjxwYH9Ps9PE357Yo0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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