SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '15e8f148b230be6dcfc7a2115213ac3726c5b9616dac18f698e7d067d4f2e37e' 
  AND token = 'GEK6lgMMbGxviL+xme9agZnJibMBfBKGSbWLnRQjass=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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