SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4363801b47add2bde9a96a68bb03246a99daaa9be476a370f5bafcdc2171274a' 
  AND token = '/vLCGiOQmnCbDws62DdusWVGtFIDiyIaUEHt4BzwALc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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