SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbeb015eaca03211ac1cecc934a2bed41d578e417527950ec5183863ca4f00d8' 
  AND token = 'clUhtnUgWQ2STMeOLsbfR+JKMARm1EDfJD/g56tcmek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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