SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f99db8c5e755f644b2b12e329aef75f244a40be26a1ca86f25b48067a9d51ea0' 
  AND token = 'E1MPyCLObOYDIjQAEuhTQZ3YAMvwAEcob6hFEil50OI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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