SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '4f491ba99289694041c48102731362a2a2ac5795531e50251b3301a5c1aded65' 
  AND token = 'YYJA12g4S5ECUCTlAulK1/l+rQxz13/itVndLr9XXWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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