SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f7d7c8aad684bd190391af3e7933cdffa75ab8036dbf3f0a0014fd92eb3ef5c' 
  AND token = 'Y2+jYj2DwiDVyzgWcGJMqhP1M5ouGdVfIO7mx5o+KJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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