SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d8fc36b3c5d94bcb289026ccc3b2642322987ba703bedb3a7f20b16c4a512ad' 
  AND token = '2N9pJBEAraip74+u3gP2a/4FBXMRhocWKOLlkup7gik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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