SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a54857c5c789e0ccdc4347820a0c6895358e8a8cb22ac1c38615eed22e46f482' 
  AND token = '6ueOt+QI9NzW2qk0jMiirUVrfivkV/pNaSADxPLhYzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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