SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '81978ba85d8a1a0b464f1f6a04f684f121e2514ab8cf5f02f4b87a167f842acf' 
  AND token = 'ZgYflRUjjC+I/NdjDhkIxH+NDrRkeaB9ti0u7Ur2WN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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