SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f35bf2d47795b447b72246ebe55f6aebc9f0bf2c83824111fa8052276f7e4f40' 
  AND token = 'H2HFwP8xFt5/qiJ+wxGcGPlKrJAHNLchzL+k7YPUMrs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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