SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4361606749b12efcabbe87980d6e8476fa4519d0f9adf88779d0954d9014c212' 
  AND token = 'oYVJOwtps7s+VFtQme7KpPjV4IhHBC+R2Ac7NbL3HWg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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