SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c38f04d7be5470cb5c1dec5eef737ed2ca7cfc64d3cffd25fd4e7a80ab59af98' 
  AND token = 'dLJpOtphcbELFE9GAzxUoZdJssX8x6aEfQBz1wwWiEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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