SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '329a7058f9dcbe6743c335bd8967bcc92770d67a6f9e39811f39401724550c82' 
  AND token = 'Kkc1lItKcnMJOAClc6DgGhFVVi+bCAiNeHlVAruP/nQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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