SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6940d007910927dd629d7817aef0afb1a99f2f1507859d74b5050b2d926f350d' 
  AND token = '9MkYk+Jt/NdDwvPAVTF3oh3B0CLxJOI0KPSYFW5/yOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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