SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dacacce68a4d6749d4651e5024e6ed1f1a929d0623beb20aadf3ee729a621f39' 
  AND token = 'I/7slQBZLYhnOmbc56Cfm+eKkYGBct10KZkbebAPDys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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