SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '091b1d43d6ed3bcc5772f331e06984bce57cd612d310d909478eddf5dba6ba38' 
  AND token = 'u5nUCz5uYypwHD1eXCRdumfE/RiJ+Z7RsJ/aMBbegNc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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