SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb9eb244e35831eac66857d70882baf38074ab65f6ac45662617ac0d076ed61a' 
  AND token = 'GpxgVQjZz1srvWYm8yKAseMd5pEGKgErhlLCGUVpvsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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