SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03547592f5d66ed3dbbb54edc4ccbff9763941ab539a619a0ab53906975c3ce9' 
  AND token = 'GPv8is2YCRVUiUJyhzVsafGPqxm70q4RaDc8RbBhHEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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