SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1c49cb23a1ba79332e1819d18e3aaac0e86febe587f631e843a311487f48ec' 
  AND token = 'A2ViNXIVo5Ga+rb2Mv2X/KupBkGCAAQ5iwtefwZAhEc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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