SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c70f4b5be52c6a7d378966457a7fae68d320a764320c09f25405306cba9ec063' 
  AND token = 'DHdMQ4XkcRvAWFP3LlIfFbCsfsMDlI2X+Ys5ABxnGP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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