SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c1920aa2c5d8497ca971245019da58320a5f4c870d8156b746209206fcbc043' 
  AND token = 'aOTTx8LBQ9fEahrAFnwh1nvld0FmPhgBdRlDYXBvwvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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