SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e51389e1a1f81179438547736957b189046726fff0b035e4218860e5882b60c0' 
  AND token = 'OZocl2Oo3fa6kISiInXGZ89qFwtXVCFdEveYaACVDUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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