SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3d6af1b559098ef1211fa26c4510433bc0bb251c90e656ce619924e91ae9f260' 
  AND token = 'T399VJeMoRle17RuUVUIJSpGnGmkaxTs9vdCwTllN18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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