SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5474ba4d1e805d21eca7bf37d98397d921be38c4eb39a2d2c471ec90e1537715' 
  AND token = 'CnsheMsBXPdEdV9lFTD4XgaQoaUDVLcKX65Cs5WByNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}