SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6d767c26ab056a6e7f556470d96d8395eaf8317402cde4cdc1b3a2d00c23b0c' 
  AND token = '/CjbcYcMOPskQvCAIi78+6oVGOj2Y8U4oHjWEG/k3G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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