SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3abc99abff5d7d86ef095a65f4fa90aa23b1d25bda3ed67676248a2db4420ab' 
  AND token = 'bZaLxgwpo0UQylNeF3PvLj+1VUa58yRIij4bJEVwR9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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