SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87d402039dcf8df6f8ed4dc8a67f589597d92c7f4aa539ae47c6aab4f4af0ed6' 
  AND token = 'JezNUQSsnfFbOCn1+lCSTkdNakyHrngPoTV5qPgDxCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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