SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21b5766bfe87420c80a63f65d678a121f7870e2b70925a3d65279b543f2e850f' 
  AND token = 'x1hK3q8/xQ4gFG/KLEnfC7cRs9+PzPqKdVYkdMUG4G4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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