SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a45b0797d97a3f8f0ffe8cefcf007f1029dc6eb6ffddabbda756df0b43ec3557' 
  AND token = 'WLqDPlCA0u1JNcI+KSapnQc82aQzcqEvFWviayma4Fw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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