SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '434979818be7d653b12039ce9b8f62b483a39323347923d19b72bd947f8efc0f' 
  AND token = 'rRoPhnYkhvZexjTo1Qsz6tBKnfFTEgKyPQbTQLom0A8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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