SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1cb5ba16018146c4627df52563d04d2de3dce804059ae29934556c70e5910a59' 
  AND token = 'vEumCmAhanegkIcyW/cbHNYB+FkujO2Qnvs57njVByI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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