SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a2d9ba3438dbf915f334ee2db2347356284c8e012f36c84a6522d68dc45d9939' 
  AND token = 'LhkPTE3krmhRGNVHDfHL88D9pioB5ysOoCQDdN9pmtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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