SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd335c2275d75e455e3ae8476b111806141aa24dfb0c2e913e9114380174e05e3' 
  AND token = 'qOKKApfSgndL8OrEF3vLOcwgPmfr+KqMwEbJkomeARU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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