SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab77b9235c183aeedbc66c15a9fdc1a53e9a0634870554637d0a1107b9261aa3' 
  AND token = 'nRcZz3e/3NhPwkl9jqOmO+Hwsn7mEnJpDRupUm1yZrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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