SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53be961a3c8189b22c1f07b4f86cff23b63a3cf88f1c16dca98231868c8da698' 
  AND token = 'gvqHMX4cZqt1TdKIy897XS40miFRfoAKAAN2ZEZ4idY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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