SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b42fbd1f98e75569715d78053755adcf7e094f1705a247d3af126bc614435666' 
  AND token = 'Bjr0aLmhzp4XJewbUjrgZDWNeMzt7+WypGFv4WNuq7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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