SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d6d97a2578761e8afdf46613da8fb71d5218b90c95f146d1402ec2434ebad4b' 
  AND token = 'ti5srlK5KDftj+ynajrsXfzskQ4BYqVTBxgzc5s4/Xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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