SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c3e8f6e5c91ca0552d76c86cc43fc759266cea2c1e1f511f46ccc58688c79bb' 
  AND token = 'J2PrPuocOmPmm3ztOIZvIk4MPkJwMAEIb9dlHg+3fEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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