SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea811aa9e46631203ffe935871d6a2de23a6fd1fa12d4bdc477a858536c9ee3e' 
  AND token = '0EF0/ZVDK2GldusbJHnki3UL22/LkGJjP8Mrrdqs9Lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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