SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3dd9de6f40284c1eac949c080691291857842ada1d026d985960e7a139b84f97' 
  AND token = '0hpUG70D2MpgIRqayEOT5gqQv+CHPL3mX3R/YJknvKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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