SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9c39c56915326b2bcfed7d3c7dc3c642f588f463249658b13682fbeb71c7fc0' 
  AND token = '8W6+3Lf2cwCtW+IDfNEUEddKyFCQtDo1xwOp6g0eiIA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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