SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5083e8420b3beef1edb96d995a4613d4327b0945d7f574bf22c8a48c2d9e455' 
  AND token = 'XzR13sKmhSeZJxTzCs+adqzTXc3acHwrjZdVQAFVT1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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