SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '193c363f6c01308276d1c5a584c4c595d2da4a09191cbed8a83acc014a5afedf' 
  AND token = 'fk6pMSvsbCI739TzRZZAxGrs/jgOghYMfgNH7UavvuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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